Yes there is some pretty good vapes under 75$ around.
For convection vaping you'll be stuck with butane powered vapes only (Vaporgenie, Vaponic,...) there is the famous VapCap too but it's not really convection as well the Vapman.
Cheap battery powered vapes are all conduction imo, I can recommand the Torch2 by TopBond (I didn't used it but tested the first iteration which was pretty decent) which is battery replacable! There is the Avant by X-Vape ( works well but battery life is 3 bowls at max), the V-Leaf by Vivant (tested, works well but it's rather big imo) and the Fenix too. I tested others cheap vapes but they are not worth it. Although there is some pretty good vapes at 75-80$ (maybe cheaper if you can get a discount), the Aria by X-Vape is pretty good but sadly no replacable battery, The Slick by Flowermate is nice too but only 3 t° presets and I don't like the threaded mp for some reasons although it's battery replacable. The X-max V2 Pro is old but still a good value too (5 t° presets and replacable battery). Like the Focus Vape pen (5 t° presets and replacable battery too) for its older version (but still available), Pro and S versions are a bit more expensive.
There is some I don't recommand: Mini-Dee by Orion, AlD Amaze Wow, Vital by X-Vape and more obscure&obsolete vapes not anymore for sale (I hope!)
And there is a lot of these cheap vapes I never used: Xs Go by AirVape, Storm Sapphire, Aura by Flowermate, Gpen Pro, PureHits by Flowermate, Gpen Nova, CFC Lite by Boundless, Novae2&Odin2 by TopBond,...
If I was you I'll stick with a replacable battery vape and you'll end with a lot less vaporizers to choose between!
Have fun!